I'd have to look through my FFTC to give you a ballpark release date Gwyn but I'm fairly sure it was originally a 4x 600ft release.I will check my Derann catalogues and get back to you with more precise info hopefully.

My own print came on one Posso 1800ft spool and it fills it to the safe maximum, so I doubt it would ever had been able to safely fit onto 3x 600ft spools with the joins being where they are even though many of these type of releases have varied at times between being a 3x or 4x 600ft release.